Conventional gas turbine engines require a substantial amount of external energy during initial startup. This is necessary in order to achieve the optimum operating speed wherein the turbine engine will sustain continued combustion. In most applications, it is known to be an important requirement for the turbine engine to start quickly and reliably.
Accordingly, gas turbine engines typically require a separate ignitor for igniting the flame. In certain circumstances, an electrically-activated pyrotechnic ignitor is preferred when economies of scale dictate this alternative starting approach. This approach will be less expensive, require less space, and weigh less than a conventional ignitor.
One approach for starting gas turbine engines which is routinely utilized is the use of a self-contained independent source of hot, pressurized exhaust gases for impingement upon turbine blades for driving the turbine rotor during the starting procedure. Independently, but simultaneously therewith, ignition is achieved within the combustion chamber either electrically or by the use of hot, pressurized exhaust gases from a separately ignited pyrotechnic. Often, the BTU energy loss during transfer of the hot exhaust gases from the conventional start cartridge by way of a small transfer line to the combustor of the turbine engine is substantial and prevents ignition from occurring. Consequently, the hot exhaust gases from the separately ignited pyrotechnic must not lose any of their BTU energy prior to injection into the combustion chamber in order to have a reliable starting process for the turbine engine. Also, for safe and reliable operation during the starting process, it is necessary that all exhaust gas sources and combustion chamber ignition operate and occur almost simultaneously without fail.
As a result of the above-mentioned factors, previously known starting systems for gas turbine engines have been designed as a compromise between reliability, cost, and multi-start capability for a specific turbine engine. It would be desirable to have a less expensive and inherently reliable approach to starting a turbine engine. More specifically, it would be desirable to have an entirely satisfactory separately ignited pyrotechnic approach to thereby eliminate the expensive requirement of having a separate electrically-activated ignitor to start a gas turbine engine.
The present invention is directed toward overcoming the various problems found in the prior art as recited above.